1. Field of the Invention
The present invention relates to a waveguide for transmitting electromagnetic waves, and an in-vehicle communication system using the waveguide.
2. Description of the Related Art
An in-vehicle communication system employing a wire harness using electric wires is well-known. FIG. 1 illustrates such a conventional in-vehicle communication system. A conventional in-vehicle communication system 100 in FIG. 1 includes a first wire harness 101 installed in an interior space, and a second wire harness 102 installed in an engine compartment. The first wire harness 101 includes a plurality of electric wires W, and a plurality of connectors 111 connected to both sides of each electric wire W. The second wire harness 102 includes a plurality of electric wires W, and a plurality of connectors 112 connected to both sides of each electric wire W. The electric wires W are tied together into a small diameter with, for example, binding tape. The connectors 111 of the first wire harness 101 are connected to the corresponding connectors 112 of the second wire harness 102 at the boundary between the interior space and the engine compartment. These connections provide transmission paths across the boundary between the respective spaces inside the vehicle.
In the in-vehicle communication system 100, the number of the electric wires W tends to increase with the increase of in-vehicle circuits, and the diameter of each bundle of the electric wires W increases accordingly. Thus, there is a problem with installation space inside the vehicle, or a problem with weight increase of the first wire harness 101 and the second wire harness 102. In addition, the number of the connectors connected between the interior space and the engine compartment increases, which requires substantial work to connect the connectors.
An in-vehicle communication system employing a waveguide has also been proposed (refer to JP 2005-176123 A). Such a conventional in-vehicle communication system can reduce a diameter and weight of transmission path, and simplify connection configuration between spaces inside a vehicle, thereby improving efficiency of connection.
The conventional waveguide is generally made of metal. Alternatively, a waveguide made of electrically-conductive plastic has been proposed (refer to JP 2002-204110 A).